Myocardial regenerative therapy is currently limited by survival and appropriate lineage commitment of adoptively transferred cells. The Notch pathway has emerged as a cardioprotective stem cell signaling pathway expressed in damaged myocardium that plays a central role in cardiac stem cell specification and differentiation to adult cardiac cell types, with Notch signaling being tightly regulated in both expression level and timing. The long-term goal of this proposal is to enhance myocardial repair and regeneration using regulated Notch signaling to enhance cellular therapy. The short-term goal is to determine molecular mechanism(s) underlying optimized Notch signaling in cardiac repair. Controlled Notch signaling will be genetically engineered into cardiac progenitor cells to produce activated Notch signaling that is both inducible and reversible. Specific aims will demonstrate: 1) Myocardial repair is increased in transgenic mice expressing stem cell-specific regulated intracellular Notch and 2) Cardiac progenitor cells engineered to express inducible Notch possess augmented regenerative capacity when adoptively transferred to infarcted hearts. Aims will be accomplished by molecular biological design to genetically engineer mouse and human cell lines in combination with biochemical, histological, and functional analyses. The significance of the proposed studies is to gain control over stem cell survival and commitment that together are profound limitations of cell-based therapeutic implementation. This targeted strategy for regulating Notch activity could be applied not only to cardiac progenitor cells but also to other stem cell types in order to promote regenerative capacity and change the paradigm for therapeutic stem cell treatment. PUBLIC HEALTH RELEVANCE: Heart disease persists as the leading cause of morbidity and mortality in the United States and throughout the world. Recent promise of cell-based therapy for treatment of cardiomyopathic injury has been stymied by limited survival, engraftment and persistence of the donated cells. Improving the reparative capacity of adoptively transferred cardiac progenitors remains a significant hurdle to therapeutic implementation. This proposal advances cardiac cell therapy through development of genetically engineered cardiac progenitors cells with enhanced properties to potentiate myocardial regeneration.